#!/usr/bin/env python3
# -*- coding: utf-8 -*-

__author__ = 'Michael Liao'

import asyncio,os,inspect,logging,functools

from urllib import parse
from aiohttp import web
from apis import APIError

def get(path):
    '''
    Define decorator @get('/path')
    '''
    def decorator(func):
        @functools.wraps(func)
        def wrapper(*args,**kw):
            return func(*args,**kw)
        wrapper.__method__='GET'
        wrapper.__route__=path
        return wrapper
    return decorator

def post(path):
    '''
    Define decorator @post('/path')
    '''
    def decorator(func):
        @functools.wraps(func)
        def wrapper(*args,**kw):
            return func(*args,**kw)
        wrapper.__method__='POST'
        wrapper.__route__=path
        return wrapper
    return decorator

def get_required_kw_args(fn):
    args=[]
    params=inspect.signature(fn).parameters
    for name,param in params.items():
        if param.kind==inspect.Parameter.KEYWORD_ONLY and param.default==inspect.Parameter.empty:
            args.append(name)
    return tuple(args)

def get_named_kw_args(fn):
    args=[]
    params=inspect.signature(fn).parameters
    for name,param in params.items():
        if param.kind==inspect.Parameter.KEYWORD_ONLY:
            args.append(name)
    return tuple(args)

def has_named_kw_args(fn):
    params=inspect.signature(fn).parameters
    for name,param in params.items():
        if param.kind==inspect.Parameter.KEYWORD_ONLY:
            return True

def has_var_kw_arg(fn):
    params=inspect.signature(fn).parameters
    for name,param in params.items():
        if param.kind==inspect.Parameter.VAR_KEYWORD:
            return  True

def has_request_arg(fn):
    sig=inspect.signature(fn)
    params=sig.parameters
    found=False
    for name,param in params.items():
        if name=='request':
            found=True
            continue
        if found and (param.kind!=inspect.Parameter.VAR_POSITIONAL and param.kind!=inspect.Parameter.KEYWORD_ONLY and param.kind!=inspect.Parameter.VAR_KEYWORD):
            raise ValueError('request parameter must be the last named parameter in function: %s%s' % (fn.__name__, str(sig)))
    return found

class RequestHandler(object):
    def __init__(self,app,fn):
        self._app=app
        self._func = fn
        self._has_request_arg = has_request_arg(fn)
        self._has_var_kw_arg = has_var_kw_arg(fn)
        self._has_named_kw_args = has_named_kw_args(fn)
        self._named_kw_args = get_named_kw_args(fn)
        self._required_kw_args = get_required_kw_args(fn)
    
    async def __call__(self,request):
        kw=None
        if self._has_var_kw_arg or self._has_named_kw_args or self._has_request_arg:
            if request.method=='POST':
                if not request.content_type:
                    return web.HTTPBadRequest('Missing Content-Type.')
                ct=request.content_type.lower()
                if ct.startswith('application/json'):
                    params=await request.json()
                    if not isinstance(params,dict):
                        return web.HTTPBadRequest('json body must be object.')
                    kw=params
                elif ct.startwith('application/x-www-form-urlencoded') or ct.startswith('multipart/form-data'):
                    params = await request.post()
                    kw=dict(**params)
                else:
                    return web.HTTPBadRequest('Unsupported Content-Type: %s' % request.content_type)
            if request.method=='GET':
                qs=request.query_string
                if qs:
                    kw=dict()
                    for k,v in parse.parse_qs(qs,True).items():
                        kw[k]=v[0]
        if kw is None:
            kw=dict(**request.match_info)
        else:
            if not self._has_var_kw_arg and self._named_kw_args:
                # remove all unamed kw:
                copy=dict()
                for name in self._named_kw_args:
                    if name in kw:
                        copy[name]=kw[name]
                kw=copy
            # check named arg:
            for k,v in request.match_info.items():
                if k in kw:
                    logging.warning('Duplicate arg name in named arg and kw args: %s' % k)
                kw[k]=v
        if self._has_request_arg:
            kw['request']=request
         # check required kw:
        if self._required_kw_args:
             for name in self._required_kw_args:
                if not name in kw:
                    return web.HTTPBadRequest(text='Missing argument: %s' % name)
        logging.info('call with args: %s' % str(kw))
        try:
            r=await self._func(**kw)
            return r
        
        except APIError as e:
            return dict(error=e.error, data=e.data, message=e.message)

def add_static(app):
    path=os.path.join(os.path.dirname(os.path.abspath(__file__)),'static')
    app.router.add_static('/static',path)
    logging.info('add static %s => %s' % ('/static/', path))

def add_route(app,fn):
    method=getattr(fn,'__method__',None)
    path=getattr(fn,'__route__',None)
    if path is None or method is None:
        raise ValueError('@get or @post not defined in %s.' % str(fn))  
    if not asyncio.iscoroutinefunction(fn) and not inspect.isgeneratorfunction(fn):
        fn=asyncio.coroutine(fn)
    logging.info('add route %s %s => %s(%s)' % (method, path, fn.__name__, ', '.join(inspect.signature(fn).parameters.keys())))
    app.router.add_route(method,path,RequestHandler(app,fn))

def add_routes(app,module_name):
    n=module_name.rfind('.')
    if n==(-1):
        mod=__import__(module_name,globals(),locals())
    else:
        name=module_name[n+1:]
        mod=getattr(__import__(module_name[:n],globals(),locals(),[name]),name)
    for attr in dir(mod):
        if attr.startswith('_'):
            continue
        fn =getattr(mod,attr)
        if callable(fn):
            method=getattr(fn,'__method__',None)
            path=getattr(fn,'__route__',None)
            if method and path:
                add_route(app,fn)

